[hpsdr] Mercury

[Lyle Johnson]

Philip Covington wrote:
> ***** High Performance Software Defined Radio Discussion List *****
> 
> Hi Phil,
> 
> Mercury:
> If we go with the AD6636, by using a couple of 74LVC16374
> <http://www.nxp.com/pip/74LVC16374ADL.html>
> 16 bit D FFs, we can either route the ADC input to the AD6636 or
> straight to the FPGA on the Mercury board.  That way we can support
> radio mode with the AD6636 and spec/oscope mode in the FPGA.  To use
> the board just as a scope or spectrum analyzer the AD6636 would not
> have to be populated on the board.  It would also allow
> experimentation with DDC in the FPGA with a fallback to the AD6636
> otherwise.

Since these are flip-flops and not MUXes, I don't understand their use. 
  Can't we just run the ADC output directly to the FPGA and to the DDC?

Do we need a larger/different family FPGA for more resources or speed to 
implement a DDC?  I'm concerned that the ADI part may not have a long 
life.  And of course, it is BGA...  If we are prepared to use BGA, we 
can get a very fast, very dense FPGA.

Lyle

> The IDT72V293 <http://www.idt.com/?genID=72V293> looks like a good
> candidate for a FIFO.  I think we'd be better off with an external
> FIFO than just SRAM.  What do you think?
> 
> Do you have recommendations for the rf front end and filters or does
> that need to wait until the first alpha board?
> 
> 73 de Phil N8VB
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